1. Field of the Invention
The present invention relates generally to an ignition apparatus mounting structure for an internal combustion engine, and more specifically to an ignition apparatus mounting structure which can improve inspection work efficiency and ignition coil performance.
2. Description of the Prior Art
As an example of ignition apparatus for internal combustion engines, Japanese Published Unexamined (Kokai) Utility Model Application No. 60-66877 discloses an ignition apparatus, in which a plurality of ignition plugs 2 are provided, respectively for engine cylinders formed within a cylinder head 1 and further each ignition coil 3 is arranged just over the ignition plug 2 to supply a high tension (voltage) to each ignition plug 2. In the prior-art ignition apparatus of this type, since the length of each high tension cord 4 connecting the ignition coil 3 to the ignition plug 2 can be minimized, there exists such an advantage that it is possible to minimize electric wave noise generated from the high tension cords 4.
In the structure of the prior-art ignition apparatus the ignition coils 3 are arranged near and over the ignition plugs 2. However, there exists another problem in that inspection work efficiency of the ignition coils 3 and the ignition plugs 2 is very low according to the arrangement of the intake system. In more detail, in the case of a V-shaped engine where two right and left cylinder lines are arranged so as to form two predetermined banks (swollen portions), since each intake pipe branched from an intake air collector and connected to each engine cylinder is arranged over the cylinder head and across the cylinder line and therefore the ignition coils 3 and the ignition plugs 2 are arranged under an intake pipe, it is impossible to inspect the ignition coils 3 and the ignition plugs 2 without removing the intake pipes from the cylinder head 1, thus reducing the inspection work efficiency of the ignition apparatus. In addition, since the ignition coils 3 are arranged on the cylinder head 1, the ignition coils 3 are subjected to the influence of heat generated from the cylinder head 1, so that the high tension generated from the ignition coils 3 often drops.